15A NCAC 02T .0114
WASTEWATER DESIGN FLOW RATES
(a) This Rule shall be used to determine wastewater flow rates for all systems covered by this Subchapter unless alternate
criteria are provided by a program specific rule and for flow used for the purposes of 15A NCAC 02H .0105. These are
minimum design daily flow rates for normal use and occupancy situations. Higher flow rates may be required where
usage and occupancy are atypical, including, those in Paragraph (e) of this Rule. Wastewater flow calculations must take
hours of operation and anticipated maximum occupancies/usage into account when calculating peak flows for design.
(b) In determining the volume of sewage from dwelling units, the flow rate shall be 120 gallons per day per bedroom.
The minimum volume of sewage from each dwelling unit shall be 240 gallons per day and each additional bedroom
above two bedrooms shall increase the volume by 120 gallons per day. Each bedroom or any other room or addition that
can reasonably be expected to function as a bedroom shall be considered a bedroom for design purposes. When the
occupancy of a dwelling unit exceeds two persons per bedroom, the volume of sewage shall be determined by the
maximum occupancy at a rate of 60 gallons per person per day.
(c) The following table shall be used to determine the minimum allowable design daily flow of wastewater facilities.
Design flow rates for establishments not identified below shall be determined using available flow data, water-using
fixtures, occupancy or operation patterns, and other measured data.
Type of Establishments
Barber and beauty shops
Barber Shops
Beauty Shops
Businesses, offices and factories
General business and office facilities
Factories, excluding industrial waste
Factories or businesses with showers or food preparation
Warehouse
Warehouse – self storage (not including caretaker residence)
Churches
Churches without kitchens, day care or camps
Churches with kitchen
Churches providing day care or camps
Fire, rescue and emergency response facilities
Fire or rescue stations without on site staff
Fire or rescue stations with on-site staff
Food and drink facilities
Banquet, dining hall
Bars, cocktail lounges
Caterers
Restaurant, full Service
Restaurant, single service articles
Restaurant, drive-in
Restaurant, carry out only
Institutions, dining halls
Deli
Bakery
Meat department, butcher shop or fish market
Specialty food stand or kiosk
Hotels and Motels
Hotels, motels and bed & breakfast facilities,
without in-room cooking facilities
Hotels and motels, with in-room cooking facilities
Resort hotels
Cottages, cabins
Self service laundry facilities
Medical, dental, veterinary facilities
Medical or dental offices
Daily Flow For Design
50 gal/chair
125 gal/booth or bowl
25 gal/employee/shift
25 gal/employee/shift
35 gal/employee/shift
100 gal/loading bay
1 gal/unit
3 gal/seat
5 gal/seat
25 gal/person (child & employee)
25 gal/person
50 gal/person/shift
30 gal/seat
20 gal/seat
50 gal/100 sq ft floor space
40 gal/seat
20 gal/seat
50 gal/car space
50 gal/100 sq ft floor space
5 gal/meal
40 gal/100 sq ft floor space
10 gal/100 sq ft floor space
75 gal/100 sq ft floor space
50 gal/100 sq ft floor space
120 gal/room
175 gal/room
200 gal/room
200 gal/unit
500 gal/machine
250 gal/practitioner/shift
Veterinary offices (not including boarding)
250 gal/practitioner/shift
Veterinary hospitals, kennels, animal boarding facilities
20 gal/pen, cage, kennel or stall
Hospitals, medical
300 gal/bed
Hospitals, mental
150 gal/bed
Convalescent, nursing, rest homes without laundry facilities
60 gal/bed
Convalescent, nursing, rest homes with laundry facilities
120 gal/bed
Residential care facilities
60 gal/person
Parks, recreation, camp grounds, R-V parks and other outdoor activity facilities
Campgrounds with comfort station, without
water or sewer hookups
75 gal/campsite
Campgrounds with water and sewer hookups
100 gal/campsite
Campground dump station facility
50 gal/space
Construction, hunting or work camps with flush toilets
60 gal/person
Construction, hunting or work camps with chemical or
portable toilets
40 gal/person
Parks with restroom facilities
250 gal/plumbing fixture
Summer camps without food preparation or laundry facilities
30 gal/person
Summer camps with food preparation and laundry facilities
60 gal/person
Swimming pools, bathhouses and spas
10 gal/person
Public access restrooms
325 gal/plumbing fixture
Schools, preschools and day care
Day care and preschool facilities
25 gal/person (child & employee)
Schools with cafeteria, gym and showers
15 gal/student
Schools with cafeteria
12 gal/student
Schools without cafeteria, gym or showers
10 gal/student
Boarding schools
60 gal/person (student & employee)
Service stations, car wash facilities
Service stations, gas stations
250 gal/plumbing fixture
Car wash facilities (if recycling water see Rule .0235)
1200 gal/bay
Sports centers
Bowling center
50 gal/lane
Fitness, exercise, karate or dance center
50 gal/100 sq ft
Tennis, racquet ball
50 gal/court
Gymnasium
50 gal/100 sq ft
Golf course with only minimal food service
250 gal/plumbing fixture
Country clubs
60 gal/member or patron
Mini golf, putt-putt
250 gal/plumbing fixture
Go-kart, motocross
250 gal/plumbing fixture
Batting cages, driving ranges
250 gal/plumbing fixture
Marinas without bathhouse
10 gal/slip
Marinas with bathhouse
30 gal/slip
Video game arcades, pool halls
250 gal/plumbing fixture
Stadiums, auditoriums, theaters, community centers
5 gal/seat
Stores, shopping centers, malls and flea markets
Auto, boat, recreational vehicle dealerships/showrooms
with restrooms
125 gal/plumbing fixture
Convenience stores, with food preparation
60 gal/100 sq ft
Convenience stores, without food preparation
250 gal/plumbing fixture
Flea markets
30 gal/stall
Shopping centers and malls with food service
130 gal/1000 sq ft
Stores and shopping centers without food service
100 gal/1000 sq ft
Transportation terminals – air, bus, train, ferry, port and dock
5 gal/passenger
(d) Design daily flow rates for proposed non-residential developments where the types of use and occupancy are not
known shall be designed for a minimum of 880 gallons per acre or the applicant shall specify an anticipated flow based
upon anticipated or potential uses.
(e) Conditions applicable to the use of the above design daily flow rates:
(1)
For restaurants, convenience stores, service stations and public access restroom facilities, higher
design daily flow rates shall be required based on higher expected usage where use is increased
because of its proximity to highways, malls, beaches, or other similar high use areas.
(2)
Residential property on barrier islands and similar communities located south or east of the Atlantic
Intracoastal Waterway used as vacation rental as defined in G.S. 42A-4 shall use 120 gallons per day
per habitable room. Habitable room shall mean a room or enclosed floor space used or intended to be
used for living or sleeping, excluding kitchens and dining areas, bathrooms, shower rooms, water
closet compartments, laundries, pantries, foyers, connecting corridors, closets, and storage spaces.
(f) An adjusted daily sewage flow design rate shall be granted for permitted but not yet tributary connections and future
connections tributary to the system upon showing that a sewage system is adequate to meet actual daily wastewater flows
from a facility included in Paragraph (b) or (c) of this Rule without causing flow violations at the receiving wastewater
treatment plant or capacity related sanitary sewer overflows within the collection system as follows:
(1)
Documented, representative data from that facility or a comparable facility shall be submitted by an
authorized signing official in accordance with Rule .0106 of this Section to the Division as follows for
all flow reduction request:
(A)
Dates of flow meter calibrations during the time frame evaluated and indication if any
adjustments were necessary.
(B)
A breakdown of the type of connections (e.g. two bedroom units, three bedroom units) and
number of customers for each month of submitted data as applicable. Identification of any
non-residential connections including subdivision clubhouses/pools, restaurants, schools,
churches and businesses. For each non-residential connection, information as identified in
Paragraph (c) of this Rule (e.g. 200 seat church, 40 seat restaurant, 35 person pool
bathhouse).
(C)
Owner of the collection system.
(D)
Age of the collection system.
(E)
Analysis of inflow and infiltration within the collection system or receiving treatment plant,
as applicable.
(F)
Where a dedicated wastewater treatment plant serves the specific area and is representative of
the residential wastewater usage, at least the 12 most recent consecutive monthly average
wastewater flow readings and the daily total wastewater flow readings for the highest average
wastewater flow month per customers as reported to the Division.
(G)
Where daily data from a wastewater treatment plant cannot be utilized or is not representative
of the project area: at least 12 months worth of monthly average wastewater flows from the
receiving treatment plant shall be evaluated to determine the peak sewage month. Daily
wastewater flows shall then be taken from a flow meter installed at the most downstream
point of the collection area for the peak month selected that is representative of the project
area. Justification for the selected placement of the flow meter shall also be provided.
(H)
An estimated minimum design daily sewage flow rate shall be taken by calculating the
numerical average of the top three daily readings for the highest average flow month. The
calculations shall also account for seasonal variations, excessive inflow and infiltration, age
and suspected meter reading/recording errors.
(2)
The Division shall evaluate all data submitted but shall also consider other factors in granting, with or
without adjustment, or denying a flow reduction request including: applicable weather conditions
during the data period (i.e. rainy or drought), other historical monitoring data for the particular facility
or other similar facilities available to the Division, the general accuracy of monitoring reports and flow
meter readings, and facility usage (i.e., resort area).
(3)
Flow increases shall be required if the calculations in Subparagraph (f)(1) of this Rule yield design
flows higher than that specified in Paragraphs (b) or (c) of this Rule.
(4)
The applicant/owner shall retain the letter of any approved adjusted daily design flow rate for the life
of the facility and shall transfer such letter to any new system owner.
History Note:
Authority G.S. 143-215.1; 143-215.3(a)(1);
Eff. September 1, 2006.